IL17A and rheumatoid arthritis: Nevertheless, recent studies have indicated that there are differences in functionality and binding capacity between the human and murine system leading to the potential failure of promising antibodies during clinical trials as exemplified by anti-IL-17 antibodies (e.g., secukinumab) [68] as an biological disease-modifying antirheumatic drugs or the phosphodiesterase 4 inhibitor apremilast [69] which were both tested successfully in mice but failed to provide clinical efficacy in patients suffering from RA [70,71,72].